Generally, an electronic serial number (hereinafter abbreviated ESN) is used in identifying a specific mobile station in the cdma2000 system and mobile stations.
FIG. 1 is a structural diagram of an electronic serial number (hereinafter abbreviated ESN) having a 32-bit length.
Referring to FIG. 1, an ESN of a mobile station consists of an upper 8-bit manufacturer code and a lower 24-bit serial number. The 8-bit part is a code uniquely allocated to each mobile station manufacturer by TIA (telecommunication industry association) authorized by FCC (Federal Communications Commission). And, the serial number part corresponds to a code granted to each mobile station by the corresponding mobile station manufacturer.
And, the ESN is used for user authentication and public long code mask (hereinafter abbreviated PLCM) generation in a mobile communication system and mobile station.
FIG. 2 is a structural diagram of a PLCM generated using an ESN.
Referring to FIG. 2, a PLCM has a 42-bit length. Upper 10-bits of the PLCM are set to a value to avoid collision with a different public long code mask, whereas lower 32-bits are set to a permutated ESN.
Meanwhile, a unique number called a user identification Module ID (hereinafter abbreviated ‘UIM_ID) is allocated to an R-UIM (removable user identity module). The UIM_ID has a 32-bit length. The UIM_ID is allocated within a range not overlapped with the ESN in an area where the TIA authorized by the FCC allocated the ESN.
It the R-UIM is allocated to a mobile communication terminal, a bit called a UIM_ID usage indicator is set to ‘1’ and UIM_ID can be provided to the position used by the ESN. Hence, in case of a mobile station to which a R-UIM is allocated, the PLCM shown in FIG. 2 includes a Permutated-UIM_ID in the lower 32-bits instead of a Permutated-ESN.
However, as the mobile communication industry expands, the demand for mobile communication terminals rises and the number of manufacturers of the mobile communication terminals increases. Hence, the ESN and UIM_ID are on the verge of being exhausted. If the ESN and UIM_ID are exhausted, collision occurs in the PLCM generated using the ESN or UIM_ID. In case that the collision occurs in the PLCM, capacity is considerably reduced as well as a problem of crosstalk may take place.